Structural characteristics and cytotoxic activity of sulfated polysaccharide from green seaweed Codium geppiorum.

We carried out an in-depth study on structural characteristics, both primary and conformational structure in solution of a novel sulfated polysaccharide from green seaweed Codium geppiorum collected in central coast of Vietnam. Primary structure of the polysaccharide was determined mainly by NMR spectra, while conformation was elucidated by using small-angle X-ray scattering method. The polysaccharide was evaluated for its cytotoxic effects on three human cancer cell lines. The results indicated that dominant structure of Codium geppiorum polysaccharide is a linear sulfated galactan, and it was composed of → 4)-β-D-Galp3S-(1 → , → 3)-β-D-Galp4S-(1 → and → 3)-β-D-Galp-(1 → residues connected through 1,3-linkages. The polysaccharide has a rodlike conformation in aqueous solution, and it shows chain association with cross-sectional radius of gyration, Rgc, around 0.70 nm as estimated from small-angle X-ray scattering measurements. The polysaccharide exhibited a significant cytotoxic activity against HT29 (colorectal adenocarcinoma), 8505c (undifferentiated thyroid carcinomas) and Hela (cervical cancer) human cancer cell lines with IC50 values of 51.85 ± 2.30, 89.30 ± 2.35 and 72.22 ± 6.73 µg/mL, respectively. [ABSTRACT FROM AUTHOR]